System and method for controlling a propulsion system of a hybrid vehicle

Abstract

The invention relates to a method for controlling a propulsion system comprising the following successive steps: - detecting a movement of a gearbox control element towards a neutral position; - moving a connecting clutch into a slipping position in which said connecting clutch allows relative rotation between a heat engine and an intermediate shaft coupled to an electric machine in response to the detection of the movement of the control element towards the neutral position; - detecting an event representative of a synchronization of the speed of the intermediate shaft and the speed of the input shaft of a gearbox; and - moving the connecting clutch from said slipping position towards the engaged position in response to the detection of said event representative of a synchronization of the speed of the intermediate shaft and the speed of the input shaft.

Description

Title of the invention: System and method for controlling a propulsion system of a hybrid vehicle technical field

[0001] The invention relates to the field of propulsion systems for hybrid vehicles.

[0002] The invention relates more particularly to a method and a control system for such propulsion systems. Technological background

[0003] In the prior art, numerous hybrid vehicle architectures combining an electric motor and an internal combustion engine are known. In particular, one architecture exists in which the electric motor is coupled to the transmission chain, between the internal combustion engine and the gearbox. The transmission chain then includes a connecting clutch interposed between the internal combustion engine and the electric motor. This connecting clutch is controlled by a control unit and is specifically designed to be held open in order to disengage the internal combustion engine and the electric motor when only the electric motor generates torque for the vehicle's wheels, thus avoiding friction losses in the internal combustion engine.

[0004] A main clutch is also interposed between the electric motor and the gearbox to disengage the electric motor and the internal combustion engine from the gearbox during gear changes. The simplest and least expensive architecture uses a manual gearbox. The main clutch is thus operated by the driver using a clutch pedal. However, depending on the driver's skill, gear changes may generate oscillations in vehicle speed, causing discomfort for the driver and passengers. Such oscillations in vehicle speed are observed after the new gear is engaged, when the clutch pedal is released, at the moment when the gears upstream and downstream of the main clutch synchronize. Summary of the invention

[0005] One idea underlying the invention is to propose a method and a control system for a propulsion system of the aforementioned type allowing to improve ride comfort during gear changes.

[0006] According to a first aspect, the invention provides a control method for a propulsion system, said propulsion system comprising: - a heat engine; - an intermediate shaft coupled to an electrical machine; - a movable connecting clutch between an engaged position in which said connecting clutch couples the internal combustion engine, and in particular its crankshaft, to the intermediate shaft and a disengaged position in which the internal combustion engine and the intermediate shaft are disengaged from each other; - a gearbox which has an input shaft and is controlled by a control device; - a main clutch which is movable between an engaged position in which said main clutch couples the intermediate shaft to the input shaft and a disengaged position in which the intermediate shaft and the input shaft are disengaged; said main clutch being controlled by a clutch pedal movable between a released position in which the main clutch is in the engaged position and a depressed position in which the main clutch is in the disengaged position; The ordering process comprises the following successive steps: - detect a movement of the control unit towards a neutral position; - move the connecting clutch into a slipping position in which said connecting clutch ensures relative rotation between the internal combustion engine and the intermediate shaft in response to the detection of the movement of the control member towards the neutral position; - detect an event representative of a synchronization of the intermediate tree and the input tree; and - move the connecting clutch from said slipping position towards the engaged position in response to the detection of said event representative of a synchronization of the speed of the intermediate shaft and the speed of the input shaft.

[0007] Thus, when the main clutch returns to its engaged position after a new gear is selected, the connecting clutch is in a slipping position. This allows for faster synchronization of the intermediate shaft speed with that of the gearbox input shaft. The variation in torque transmitted by the main clutch during the synchronization of the intermediate shaft and the gearbox input shaft is therefore smaller, which helps to reduce vehicle speed fluctuations.

[0008] In addition, since the connecting clutch is controlled by the control system, after the synchronization of the intermediate shaft and the input shaft, the synchronization of the crankshaft of the internal combustion engine and the intermediate shaft can be done in such a way as to limit the variations of the torque transmitted by the connecting clutch.

[0009] According to some embodiments, such a control method may include one or several of the following characteristics.

[0010] According to one embodiment, the speed of the intermediate shaft and the speed of the input shaft are compared and the event representing a synchronization of the intermediate shaft and the input shaft is detected when said speeds are equal.

[0011] According to one embodiment, the control method comprises, prior to the detection of the movement of the control element towards the neutral position, the following steps: - detect an event representative of a movement of the main clutch from the engaged position towards the disengaged position; and - move the connecting clutch from the engaged position towards the disengaged position to a setpoint position in which the connecting clutch does not slip, in response to the detection of the event representative of a movement of the main clutch from the engaged position towards the disengaged position.

[0012] This allows the slipping position of the connecting clutch to be reached more quickly when a movement of the control member towards the neutral position is detected.

[0013] According to one embodiment, in response to the detection of the movement of the control member towards the neutral position, the internal combustion engine and / or the connecting clutch are controlled so as to control a speed difference between an internal combustion engine speed and an intermediate shaft speed to a setpoint value.

[0014] According to one embodiment, an event representing a movement of the main clutch from the engaged position towards the disengaged position beyond a threshold is detected, and the electric machine is controlled as a function of a variable representing the speed of the input shaft so as to maintain a rotation of said heat engine until the event representing a synchronization of the intermediate shaft and the input shaft is detected.

[0015] Thus, the speed of the intermediate shaft can be maintained close to the speed of the input shaft. The difference between the acceleration of the intermediate shaft and that of the gearbox input shaft at the moment of synchronization is therefore small. This makes it possible to reduce the torque transmitted by the main clutch before synchronization and, consequently, to further limit the variation in the torque transmitted by the main clutch during the synchronization of the intermediate shaft and the input shaft. Vehicle speed oscillations are therefore further limited.

[0016] According to one embodiment, a movement of the gearbox control element representative of a gear change is detected; and - When the displacement corresponds to a new gear engaged that is higher than the previous one, the electric machine is controlled so that the rotational speed of the intermediate shaft is controlled by a setpoint value Vintervalshaft = VO + Cl; where: - VO: the speed of the input shaft 9 of the gearbox 10 (curve 59); and - Cl: a constant, for example between 1 and 50 revolutions per minute; and - when the displacement corresponds to a new gear engaged that is lower than the previous one, the electric machine is controlled so that the rotational speed of the intermediate shaft is controlled by Vintervalshaft = VO - C2; where: - C2: a constant, for example between 1 and 50 revolutions per minute.

[0017] According to one embodiment, in response to the detection of the event representing a synchronization of the intermediate shaft and the input shaft, the electric machine is controlled in torque according to a decreasing torque setpoint and the thermal engine is controlled according to said decreasing torque setpoint of the electric machine in order to compensate for the decrease in the torque of the electric machine and a signal representing a position of an accelerator pedal.

[0018] According to another embodiment, an event representing a movement of the main clutch from the engaged position towards the disengaged position beyond a threshold is detected, and the internal combustion engine is controlled according to the speed of the input shaft until an event representing synchronization of the intermediate shaft and the input shaft is detected. This also makes it possible to limit oscillations in the vehicle's speed.

[0019] According to one embodiment, a movement of the gearbox control element representative of a gear change is detected; and - When the displacement corresponds to a new gear ratio that is higher than the previous one, the internal combustion engine is controlled so that its speed is regulated to Vengine = V0 + Cl; with: - V0: the speed of the gearbox input shaft; and - Cl: a constant, for example between 1 and 50 revolutions per minute; and - When the displacement corresponds to a new gear ratio that is lower than the previous one, the internal combustion engine is controlled so that its speed is regulated to Vengine = V0 - C2; with: - C2: a constant, for example between 1 and 50 revolutions per minute.

[0020] According to a second aspect, the invention also provides a control system for a propulsion system, said propulsion system comprising: - a heat engine; - an intermediate shaft coupled to an electrical machine; - a movable connecting clutch between an engaged position in which said connecting clutch couples the internal combustion engine, and in particular its crankshaft, to the intermediate shaft and a disengaged position in which the internal combustion engine and the intermediate shaft are disconnected from each other; - a gearbox which has an input shaft and is controlled by a control device; - a main clutch that is movable between an engaged position in which said main clutch couples the intermediate shaft to the input shaft and a disengaged position in which the intermediate shaft and the input shaft are disengaged; said main clutch being controlled by a clutch pedal movable between a released position in which the main clutch is engaged and a depressed position in which the main clutch is disengaged; said control system being configured to: - detect a movement of the control unit towards a neutral position; - move the connecting clutch into a slipping position in which said connecting clutch ensures relative rotation between the internal combustion engine and the intermediate shaft in response to the detection of the movement of the control member towards the neutral position; - detect an event representative of a synchronization of the intermediate tree and the input tree; and - move the connecting clutch from said slipping position towards the engaged position in response to the detection of said event representative of a synchronization of the intermediate shaft and the input shaft.

[0021] According to embodiments, such a control system may include one or more of the following characteristics.

[0022] According to one embodiment, the control system is configured to: - detect an event representative of a movement of the main clutch from the engaged position towards the disengaged position; and - move the connecting clutch from the engaged position towards the disengaged position to a setpoint position in which the connecting clutch does not slip, in response to the detection of the event representative of a movement of the main clutch from the engaged position towards the disengaged position.

[0023] According to one embodiment, the control system is configured to control the internal combustion engine and / or the connecting clutch so as to control a speed difference between an internal combustion engine speed and an intermediate shaft speed to a setpoint value in response to the detection of the movement of the control member towards the neutral position.

[0024] According to one embodiment, the control system is configured to: - detect an event representative of a displacement of the main clutch the engaged position towards the disengaged position beyond a threshold; and - control the electric machine as a function of a variable representing a speed of the input shaft until the event representing a synchronization of the intermediate shaft and the input shaft is detected.

[0025] According to one embodiment, the control system is configured to: - to control the electric machine's torque according to a decreasing torque setpoint in response to the detection of the event representing synchronization of the intermediate shaft and the input shaft, and - control the internal combustion engine according to the aforementioned decreasing torque setpoint of the electric machine in order to compensate for the decrease in the torque of the electric machine and a signal representing a position of an accelerator pedal.

[0026] According to another embodiment, the control system is configured to: - detect an event representative of a movement of the main clutch from the engaged position towards the disengaged position beyond a threshold; and - control the internal combustion engine as a function of a variable representing the speed of the input shaft until the event representing a synchronization of the intermediate shaft and the input shaft is detected.

[0027] According to a third aspect, the invention relates to a motor vehicle comprising: - a heat engine; - an intermediate shaft coupled to an electrical machine; - a movable connecting clutch between an engaged position in which said connecting clutch couples the internal combustion engine, and in particular its crankshaft, to the intermediate shaft and a disengaged position in which the internal combustion engine and the intermediate shaft are disengaged from each other; - a gearbox which has an input shaft and is controlled by a control device; - a main clutch that is movable between an engaged position in which said main clutch couples the intermediate shaft to the input shaft and a disengaged position in which the intermediate shaft and the input shaft are disengaged; said main clutch being controlled by a clutch pedal movable between a released position in which the main clutch is engaged and a depressed position in which the main clutch is disengaged; and - a control system as described above.

[0028] According to one embodiment, the electric machine is coupled to the intermediate shaft, directly or indirectly, in particular by a gearbox. The gearbox has, for example, a reduction ratio between 1 and 4, and preferably of the order of 2.2. Brief description of the figures

[0029] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings.

[0030] Fig. 1 is a schematic representation of a hybrid vehicle according to one embodiment.

[0031] Fig. 2 is a graph illustrating the evolution of the state of the propulsion system equipment according to the prior art during a change of speed ratio to a higher speed ratio.

[0032] Fig. 3 is a graph illustrating the evolution of the state of the propulsion system equipment according to the prior art during a change of speed ratio to a lower speed ratio.

[0033] Fig. 4 is a diagram illustrating the steps of a method for controlling the propulsion system according to a first embodiment, during a change in speed ratio.

[0034] Fig. 5 is a graph similar to that of Fig. 2 when implementing the control method according to the first embodiment, for a change of speed ratio to a higher speed ratio.

[0035] Fig. 6 is a graph similar to that of Fig. 5 when implementing the control method according to the first embodiment, for a change of speed ratio to a lower speed ratio.

[0036] Fig.7 is a graph similar to that of Fig.2 when implementing a control method according to a second embodiment, for a change of speed ratio to a higher speed ratio.

[0037] Fig. 8 is a graph similar to that of Fig. 7 when implementing the control method according to the second embodiment, for a change of speed ratio to a lower speed ratio.

[0038] The [Fig.9] is a graph similar to that of the [Fig.2] during the implementation of a control method according to a third embodiment, for a change of speed ratio to a higher speed ratio.

[0039] The [Fig. 10] is a graph similar to that of the [Fig.9] during the implementation of the control method according to the third embodiment, for a change of speed ratio to a lower speed ratio.

[0040] Figure 11 is a graph similar to that of Figure 2 during the implementation of a control method according to a fourth embodiment, for a changing gear ratio to a higher gear ratio. Description of the implementation methods

[0041] In relation to [Fig.1], a propulsion system for a hybrid vehicle is described below according to an example of an embodiment.

[0042] The hybrid vehicle has at least two axles 1, 2, of which at least one, here the front axle 1, is coupled to the propulsion system.

[0043] The propulsion system includes a heat engine 3 whose crankshaft is coupled to a flywheel 4, for example a double flywheel equipped with a torsional damper. The propulsion system also includes an electric machine 5 and a connecting clutch 6 which is arranged along the torque transmission path between the heat engine 3 and the electric machine 5.

[0044] The connecting clutch 6 is suitable for coupling the heat engine 3 to an intermediate shaft 7, said intermediate shaft 7 being coupled to the electric machine 5. In the embodiment shown, the intermediate shaft 7 is indirectly coupled to the electric machine 5 by a reduction gear 8. However, in other embodiments not shown, the electric machine 5 is directly coupled to the intermediate shaft 7. Thus, the intermediate shaft 7 may, for example, be coaxial with the axis of rotation of the rotor of the electric machine 5 and consequently be formed at least partially by the rotor shaft of the electric machine 5.

[0045] The intermediate shaft 7 is further coupled to an input shaft 9 of the gearbox 10 by a main clutch 11. The output shaft of the gearbox 10 is coupled by a differential device 12 to the left 13 and right 14 drive shafts of the front axle 1.

[0046] The internal combustion engine 3 is controlled by an engine control unit 15. To do this, the engine control unit 15 receives, in particular, the following signals: - a signal representative of the speed of the internal combustion engine 3, this signal being delivered for example by a speed sensor 16 measuring the rotational speed of the flywheel 4; - a signal representing the position of the accelerator pedal 17 as measured by a position sensor 18; and - various information available on communication bus 19 which is connected to the other vehicle control equipment.

[0047] The electric machine 5 is supplied with electrical energy and controlled by an inverter 20 which is connected via the communication bus 19 to a hybrid control unit 21. The inverter 20 is connected to the high-voltage electrical network 24 and, in particular, to the high-voltage battery 22. The inverter 20 is also connected to a DC / DC voltage converter 23 which is connected to a low-voltage electrical network Voltage 25, and in particular the Low Voltage battery 26, is configured to convert the voltage level delivered by the Low Voltage battery 26 to the voltage level required by the High Voltage electrical network 24. The low voltage network has a voltage between 9V and 30V, and preferably 12V for a passenger vehicle or a light vehicle for transporting goods or people, and 24V for a heavy vehicle intended for transporting goods or people or for construction. The high voltage network corresponds to a voltage between 40V and 1000V depending on the level of hybridization of the vehicle and the power of the electric machine 5, and preferably 48V.

[0048] The connecting clutch 6 is actuated by a clutch actuator 39, which allows it to move between an engaged position in which the internal combustion engine 3 and the electric machine 5 are coupled to each other and a disengaged position in which the internal combustion engine 3 and the electric machine 5 are disengaged. The clutch actuator 39 is connected to the hybrid control unit 21 and powered by the low-voltage battery 26 via the low-voltage network 25.

[0049] The main clutch 11 is operated by the driver by means of a clutch control device, such as a clutch pedal 27. When the clutch pedal 27 is not pressed, the main clutch 11 is in the engaged position in which it couples the intermediate shaft 7 to the input shaft 9 of the gearbox 10. When the driver presses the clutch pedal 27, the main clutch 11 is moved towards the disengaged position in which the intermediate shaft 7 and the input shaft 9 of the gearbox 10 are disengaged.

[0050] In one embodiment, the main clutch 11 is controlled by the clutch pedal 27 by means of a hydraulic control system. Such a hydraulic control system comprises a master cylinder 28 associated with the clutch pedal 27, a slave cylinder 29 associated with the main clutch 11, and a hydraulic linkage 30 connecting the master cylinder 28 to the slave cylinder 29. The clutch pedal 27 is associated with a position sensor 31 that provides information representing the position of the clutch pedal 27 between a released position corresponding to the engaged position of the main clutch 11 and a depressed position corresponding to the disengaged position. The position sensor 31 is connected to the engine control unit 15 and optionally to the hybrid control unit 21.

[0051] The gearbox 10 is controlled by the driver by means of a gearbox control element 32, such as a gear lever. The gearbox control element 32 is associated with a position sensor 33 which provides the hybrid control unit 21 with information representing the position of said control element 32. This information makes it possible to determine the gear ratio of the gearbox 10 which is engaged and to estimate the driver's intention to change gear.

[0052] The hybrid vehicle includes other sensors which are connected to the hybrid control unit 21 and the engine control unit 15, such as a sensor providing information representative of the steering wheel angle 34, a sensor 35 providing information representative of the position of the brake pedal 36 or the pressure exerted on it, a sensor 37 providing information representative of the wheel speed and a sensor 38 providing information representative of the speed of the input shaft 9 of the gearbox 10.

[0053] Hereafter, the term "control system" will refer to the element(s) that control the propulsion system equipment, and in particular the connecting clutch 6, the electric machine 5, and the internal combustion engine 3. In the embodiment shown, the control system includes, in particular, the hybrid control unit 21 and the engine control unit 15. However, the control system can be implemented in various forms, either as a unit or distributed, using hardware and / or software components. Usable hardware components include ASICs, FPGAs, and microprocessors. Software components can be written in various programming languages, for example, C, C++, Java, or VHDL. This list is not exhaustive.

[0054] In particular, according to one embodiment, the functionalities of the control system which will be described below are partially or fully integrated into a control unit which is incorporated into the hydraulic control system of the main clutch 11.

[0055] Fig. 2 is a graph illustrating the evolution of the state of the propulsion system equipment according to the prior art during a change of speed ratio to a higher speed ratio.

[0056] In [Fig.2] (as in the following figures 3 and 5 to 11), curves 50 to 60 have the following meanings: - the first curve 50 illustrates the position of the accelerator pedal 17; - the second curve 51 illustrates the position of the clutch pedal 27; - the third curve 52 illustrates the position of the control unit 32; - the fourth curve 53 illustrates the torque delivered by the internal combustion engine 3; - the fifth curve 54 illustrates the maximum torque that can be transmitted by the main clutch 11; - the sixth curve 55 illustrates the torque delivered by the electric machine 5; - the seventh curve 56 illustrates the maximum torque that can be transmitted by the connecting clutch 6; - the eighth curve 57 illustrates the speed of the vehicle; - the ninth curve 58 illustrates the operating regime of the internal combustion engine 3; - the tenth curve 59 illustrates the speed of the input shaft 9 of the gearbox 10; and - the eleventh curve 60 illustrates the speed of the intermediate shaft 7, which is where applicable correlated to the speed of the electric machine 5 by the reduction ratio of the reducer 8.

[0057] The operation of changing a speed ratio can be broken down into four successive phases respectively, designated PHASE I, PHASE II, PHASE III and PHASE IV in the figures.

[0058] In a preliminary phase to the operation of changing a gear ratio, the speed of the input shaft 9 of the gearbox 10 (tenth curve 59) is correlated to the speed of the vehicle (eighth curve 57) by the reduction ratio corresponding to the gear ratio of the gearbox 10 which is engaged.

[0059] The speed of the heat engine 3 (ninth curve 58) and the speed of the intermediate shaft 7 (eleventh curve 60) are equal as long as the connecting clutch 6 is in the engaged state, which is the case during a gear change operation according to the prior art, as shown in [Fig.2].

[0060] The first phase (PHASE I) corresponds to the release of the accelerator pedal 17, visible on the first curve 50.

[0061] The second phase (PHASE II) corresponds to the movement of the clutch pedal 27 towards the depressed position (second curve 51). This movement results in the main clutch 11 moving towards the disengaged position and, consequently, in a decrease in the maximum torque transmitted by the main clutch 11 (fifth curve 54) until it becomes zero. The speed of the internal combustion engine 3 (ninth curve 58) and the speed of the intermediate shaft 7 (eleventh curve 60) then decrease due to residual internal friction and thus become lower than the speed of the input shaft 9 of the gearbox 10 (tenth curve 59).

[0062] Depending on the speed of execution of the driver, phases I and II are likely to overlap.

[0063] The third phase (PHASE III) corresponds to the actuation of the control member 32 of the gearbox 10 (third curve 52) in two stages. In the first stage, the control member 32 of the gearbox 10 is moved to disengage the previous gear. In the second stage, the control member 32 of the gearbox 10 is moved to engage a higher gear, i.e., one with a lower reduction ratio than the previous gear. Thus, the speed of the input shaft 9 of the gearbox speeds 10 (tenth curve 59) is lower when the higher gear ratio is engaged.

[0064] Depending on the speed of execution of the driver, phases II and III are also likely to overlap.

[0065] Phase IV corresponds to the movement of the clutch pedal 27 towards the released position (second curve 51) and the pressing of the accelerator pedal 17 (first curve 50). During this phase IV, as soon as the torque transmitted by the main clutch 11 becomes greater than 0 again (fifth curve 54), the speed of the internal combustion engine 3 (ninth curve 58) and the speed of the intermediate shaft 7 (eleventh curve 60) increase until they synchronize with the speed of the input shaft 9 of the gearbox 10 (tenth curve 59).

[0066] During this phase IV, oscillations in the vehicle speed are observed in the area referenced A on [Fig.2] (eighth curve 57). These oscillations are due to the abrupt variation of the torque transmitted by the main clutch 11 during the synchronization of the speed of the intermediate shaft 7 (eleventh curve 60) with that of the input shaft 9 of the gearbox 10 (tenth curve 59).

[0067] When the main clutch 11 slips, as long as the intermediate shaft 7 (eleventh curve 60) is not synchronized with the input shaft 9 of the gearbox 10 (tenth curve 59), the torque transmitted by the main clutch 11 depends primarily on the maximum torque that can be transmitted by the main clutch and, consequently, on the pressure exerted by the hydraulic system's slave cylinder on the clutch. The transmitted torque thus depends on the position of the clutch pedal 27. The more the clutch pedal 27 is depressed, the lower the pressing force exerted by the pressure plate on the friction disc, which limits the transmitted torque. Conversely, if the clutch pedal 27 is partially released, the pressing force increases, allowing a greater torque transfer.

[0068] Thus, the torque transmitted by the main clutch 11 depends in particular on the difference between the speed of the intermediate shaft 7 (eleventh curve 60) and that of the input shaft 9 of the gearbox 10 (tenth curve 59) during the synchronization of the intermediate shaft 7 and the input shaft 9 of the gearbox 10. The greater this speed difference, the longer the synchronization. Thus, for the same clutch pedal release speed, the torque transmitted by the main clutch 11 will be greater when the difference between the speed of the intermediate shaft 7 and that of the input shaft 9 of the gearbox 10 is greater.

[0069] Therefore, depending on the position of the clutch pedal 27 and consequently on the value of the maximum torque transmissible by the main clutch 11, the torque transmitted by the main clutch 11 is likely to be much greater than that which it transmits when synchronization is achieved. This sudden variation in the torque transmitted in the main clutch 11 excites the rigidity of the transmission shafts, which produces the undesirable undulations in vehicle speed, as illustrated in the referenced area A.

[0070] As soon as synchronization is achieved, the torque Csynch which is transmitted by the main clutch 11 corresponds to the following equation: Csynch = (13+14) / (11+I2+I3+I4) * Cword + (11+12) / (I1+I2+I3+I4) * Cload ; with It: the moment of inertia of the engine group, i.e. the elements of the propulsion system upstream of the connecting clutch 6 (including the crankshaft, the flywheel, the input of the connecting clutch 6 and all the inertia connected by the accessory belt); 12: the moment of inertia of the propulsion system elements arranged between the connecting clutch 6 and the main clutch 11 (output of the connecting clutch 6, electric machine 5, reducer 8, intermediate shaft 7 and input of the main clutch 11); 13: the moment of inertia of the elements of the propulsion system downstream of the main clutch 11 (output of the main clutch 11, engaged shafts and gears of the gearbox, transmission shafts, differential); 14: the vehicle's inertia (including the vehicle's mass, wheels, and axles); Cmot: the engine torque (fourth curve 53); and Ccharg: the vehicle load torque corresponding to rolling resistance, aerodynamic forces and the vehicle weight due to the road slope.

[0071] Since the sum of the moments of inertia 13+14 is much greater than the sum of the moments of inertia 11+12, the torque Csynch transmitted by the main clutch 11 when synchronization is obtained depends largely on the engine torque Cmot, which is likely to be relatively low during synchronization, which explains the sudden drop in the torque transmitted in the main clutch 11 as soon as synchronization is obtained.

[0072] Figure 3 is a graph similar to that of Figure 2, but during a downshift. During phase IV, in the area referenced A, the same phenomenon of vehicle speed oscillations (eighth curve 57) is also observed, which is also explained by a sudden decrease in the torque transmitted by the clutch.

[0073] A first embodiment of the invention is described below in relation to Figures 4, 5, and 6, which allows for limiting, or even eliminating, the aforementioned undulations during a gear change. Figure 4 is a diagram illustrating the control steps implemented by the control system, while Figures 5 and 6 illustrate the state of the propulsion system equipment. tively during a gear change to a higher gear and to a lower gear.

[0074] The preliminary phase to the operation of changing a gear ratio is identical to that described above in relation to [Fig.2]: a gear ratio of the gearbox 10 is engaged and the accelerator pedal 17 is at least partially depressed (first curve 50 - figures 5 and 6).

[0075] During phase I, the control system detects that the accelerator pedal 17 moves towards the released position (step 100, [Fig.4]). This movement of the accelerator pedal 17 is visible in Figures 5 and 6 (first curve 50).

[0076] During phase II, the control system detects a movement of the clutch pedal 27 towards the depressed position (step 101, [Fig. 4]). This movement of the clutch pedal 27 is also visible in Figures 5 and 6 (second curve 51).

[0077] As soon as a movement of the clutch pedal 27 has been detected, the control system implements two processes in parallel until the new gear ratio is engaged (step 130, [Fig.4]), one aimed at controlling the connecting clutch 6 and the internal combustion engine 3 (steps 102 to 109, [Fig.4]) and the other aimed at controlling the electric machine 5 (steps 120 to 124, [Fig.4]).

[0078] Thus, as soon as a movement of the clutch pedal 27 towards the disengaged position is detected, the control system moves the connecting clutch 6 (steps 102 and 103, [Fig. 4]) towards its fully disengaged position, up to a setpoint position ensuring that said connecting clutch 6 does not slip. This setpoint position corresponds to a torque transmission capacity greater than Csynch, as defined above. The movement of the connecting clutch 6 during phase II can be seen in Figures 5 and 6 (seventh curve 56).

[0079] These steps are optional and are only intended to reach the slipping position of the connecting clutch as quickly as possible during the following steps (steps 105 and 106, [Fig.4]) which will be described below.

[0080] The control system is configured to detect phase III, i.e., that the position of the control element 32 of the gearbox 10 corresponds to the neutral position of the gearbox 10 (step 104, [Fig. 6]). The movement of the position of the control element 32 of the gearbox to neutral is visible in Figures 5 and 6 (third curve 52). In response to the detection of such a position of the control element 32, the control system again moves the connecting clutch 6 towards the disengaged position so that it reaches a slipping position, in which said connecting clutch 6 ensures relative rotation between the crankshaft of the internal combustion engine 3 and the intermediate shaft 7 (steps 105, 106). and 107, [Fig. 4]). In other words, in this slipping position, the connecting clutch 6 ensures a speed difference between the speed of the internal combustion engine 3 (ninth curve 58) and the speed of the intermediate shaft 7 (eleventh curve 60). According to one embodiment, the control system detects that said slipping position is reached as soon as a difference between the speed of the internal combustion engine 3 (ninth curve 58) and the speed of the intermediate shaft 7 (eleventh curve 60) is detected.

[0081] Subsequently, during phase IV, the control system compares the position of the clutch or clutch pedal 27 to a position threshold that corresponds to a position of the main clutch 11 located, in its travel towards the engaged position, before the slip point (step 108, [Fig. 4]), i.e., the point from which said main clutch 11 begins to slip. As soon as the control system has detected a position of the clutch or clutch pedal 27 beyond said position threshold during the clutch travel, the internal combustion engine 3 and / or the connecting clutch 6 are controlled so that the connecting clutch 6 slips, i.e., that there is relative rotation between the crankshaft of the internal combustion engine 3 and the intermediate shaft 7 (step 109, [Fig. 4]).To achieve this, the internal combustion engine 3 and / or the connecting clutch 6 are controlled to regulate the speed difference between the speed of the internal combustion engine 3 (ninth curve 58) and the speed of the intermediate shaft 7 (eleventh curve 60) to a setpoint value. This setpoint value is, for example, between 1 and 50 revolutions per minute. Figures 5 and 6 thus show a speed difference between the speed of the internal combustion engine 3 (ninth curve 58) and the speed of the intermediate shaft 7 (eleventh curve 60).

[0082] As previously indicated, as soon as a movement of the clutch pedal 27 has been detected (PHASE II), the control system implements, in parallel with the aforementioned steps 102 to 109 aimed at controlling the connecting clutch 6 and the internal combustion engine 3, a second process aimed at controlling the electric machine 5 (steps 120 to 123, [Fig.4]).

[0083] The control system compares the position of the clutch or clutch pedal 27 to a position threshold which corresponds to a position of the main clutch 11, during a disengagement stroke, before the slip point, i.e. the aforementioned point from which said main clutch 11 begins to slip.

[0084] As soon as the control system has detected a position of the clutch or clutch pedal 27 beyond said position threshold during the disengagement stroke, the control system controls the electric machine 5 according to the speed of the input shaft 9 of the gearbox 10 (step 120, [Fig.4]).

[0085] More specifically, the control system controls the electric machine 5 of so that the rotational speed of the intermediate shaft 7 (eleventh curve 60) is controlled by a setpoint value Varbæjnter = V0 + Cl (step 121, [Fig.4]); with: - V0: the speed of the input shaft 9 of the gearbox 10 (tenth curve 59); and - Cl: a constant, for example between 1 and 50 revolutions per minute.

[0086] During phase III, the control system detects a movement of the control member 32 of the gearbox 10 (third curve 52) representative of a change in gear ratio (step 122, [Fig.4]).

[0087] If the new gear engaged is a lower speed ratio than the previous one, the control system controls the electric machine 5 so that the rotational speed of the intermediate shaft 7 (eleventh curve 60) is controlled by Vintershaft = V0 - C2 (step 123, [Fig. 4]); with: - V0: the speed of the input shaft 9 of the gearbox 10 (tenth curve 59); and - C2: a constant, for example between 1 and 50 revolutions per minute.

[0088] Thus, as shown in [Fig.5], when a new gear ratio higher than the previous one is engaged, the speed of the intermediate shaft 7 (eleventh curve 60) decreases while remaining slightly higher than the new speed of the input shaft 9 of the gearbox 10 (tenth curve 59) corresponding to the new gear ratio engaged.

[0089] On the other hand, as can be seen in [Fig.6], when the new gear ratio which is engaged is lower than the previous one, the speed of the intermediate shaft 7 (eleventh curve 60) increases to approach the new speed of the input shaft 9 of the gearbox 10 (tenth curve 59) corresponding to the new gear ratio engaged.

[0090] During phase IV, the control system compares the rotational speed of the input shaft 9 of the gearbox 10 (tenth curve 59) to that of the intermediate shaft 7 (eleventh curve 60) and detects a press on the accelerator pedal 17. As soon as the speeds are synchronized (step 130, [Fig.4]), the control system controls the electric machine 5 with a torque setpoint decreasing over time so that the torque it generates (sixth curve 55) gradually decreases until it reaches zero torque (step 140, [Fig.4]).

[0091] Furthermore, when the accelerator pedal 17 is depressed, which is likely to correspond to the case in [Fig. 5] where the gear change is to a higher gear, the control system also controls the torque of the internal combustion engine (fourth curve 53) as a function of the decreasing torque setpoint of the electric motor 5 and the position of the accelerator pedal 17 so that the torque delivered by the electric motor 5 (sixth curve 55) is progressively transferred to the internal combustion engine 3 and that the torque delivered by the internal combustion engine 3 (fourth curve 53) corresponds to a corresponding torque setpoint responding to the position of the accelerator pedal 17 (first curve 50) (step 140, [Fig.4]).

[0092] On the other hand, in the case of [Fig.6], in which the gear change is to a lower gear, the user does not press the accelerator pedal 17 in phase IV and the torque delivered by the internal combustion engine 3 (fourth curve 53) remains zero.

[0093] The connecting clutch 6 is then torque controlled so as to reduce the speed difference between the speed of the internal combustion engine 3 (ninth curve 58) and the speed of the intermediate shaft 7 (eleventh curve 60) until it becomes zero (steps 150 and 151, [Fig.4]).

[0094] As soon as the speed of the heat engine 3 (ninth curve 58) and that of the intermediate shaft 7 (eleventh curve 60) are synchronized, the connecting clutch 6 is moved up to its maximum transmissible torque capacity (step 160, [Fig.4]).

[0095] The advantages arising from the process described above are as follows.

[0096] First, during phase IV, corresponding to the movement of the clutch pedal 27 towards the released position (second curve 51), with the connecting clutch 6 in a slipping position (seventh curve 56), only the speed of the drive system components located between the connecting clutch 6 and the main clutch 11 needs to be synchronized with the speed of the input shaft 9 of the gearbox 10. Since the inertia of the components to be synchronized is lower, the synchronization of the speed of the intermediate shaft 7 with that of the input shaft 9 of the gearbox 10 occurs more quickly. The value of the torque transmitted by the main clutch 11 just before the synchronization of the speeds of the intermediate shaft 7 and the input shaft 9 of the gearbox 10 is therefore lower. This reduces the transmission excitations when synchronization is achieved.

[0097] Secondly, since during the synchronization phase the electric machine 5 is controlled so that the speed of the intermediate shaft 7 is maintained close to the speed of the input shaft 9 of the gearbox 10, the difference between the acceleration of the intermediate shaft 7 (eleventh curve 60) and that of the input shaft 9 of the gearbox 10 (tenth curve 59) at the moment they synchronize is small. The torque transmitted by the main clutch 11 before synchronization is therefore small.

[0098] Furthermore, since the connecting clutch 6 is kept in slippage, the torque transmitted by the main clutch 11 immediately after the synchronization of the intermediate shaft 7 with the input shaft 9 of the gearbox 10 is obtained is equal to: CSynch (13+14) / (I2+I3+I4) Cemb-connex-!- (12) / (I2+I3+I4) Ccharg J with Cemb_connex of torque transmitted by the connection clutch 6.

[0099] Thus, since the sum of the inertias 13+14 is much greater than the inertia 12, the torque Csynch transmitted by the main clutch 11 when synchronization is achieved is approximately equal to the torque transmitted by the connecting clutch 6 Cemb_COnnex, which is low. The variation in the torque transmitted by the main clutch 11 during the synchronization of the intermediate shaft 7 with the input shaft 9 of the gearbox 10 is therefore small.

[0100] Finally, lastly, as the connecting clutch 6 is controlled by the control system, the difference between the acceleration of the engine speed and that of the intermediate shaft 7 is small, which also makes it possible to avoid a sudden change in the torque transmitted by the connecting clutch 6 when the synchronization of the internal combustion engine 3 and the intermediate shaft 7 is achieved.

[0101] Figures 7 and 8 represent the implementation of a control method according to a second embodiment respectively during a speed change towards a higher speed ratio and towards a lower speed ratio.

[0102] In this second embodiment, the control method is simplified in that it only acts on the connection clutch 6 to limit undesirable undulations in the vehicle speed.

[0103] In this embodiment, as soon as a movement of the clutch pedal 27 towards the disengaged position has been detected, the control system moves the connecting clutch 6 towards its fully disengaged position until a slipping position, in which said connecting clutch 6 transmits a drag torque between the crankshaft of the internal combustion engine 3 and the intermediate shaft 7.

[0104] Subsequently, the control system compares the rotational speed of the input shaft 9 of the gearbox 10 (tenth curve 59) to that of the intermediate shaft 7 (eleventh curve 60). Once the input shaft 9 of the gearbox 10 and the intermediate shaft 7 are synchronized, the connecting clutch 6 is then torque-controlled so as to reduce the speed difference between the speed of the internal combustion engine 3 (ninth curve 58) and the speed of the intermediate shaft 7 (eleventh curve 60) until it becomes zero.

[0105] Thus, only the drive system components located between the connecting clutch 6 and the main clutch 11 are synchronized with the input shaft 9 of the gearbox 10, thereby achieving this synchronization more quickly. The value of the torque transmitted by the main clutch 11 just before the synchronization of the intermediate shaft 7 and the input shaft 9 of the gearbox 10 is lower, which reduces transmission excitations when synchronization is achieved.

[0106] Figures 9 and 10 illustrate the implementation of a control method according to a third embodiment respectively during a change of speed towards a higher speed ratio and towards a lower speed ratio.

[0107] In this third simplified embodiment, the control method is simplified in that it only acts on the connecting clutch 6 and the internal combustion engine 3 to limit undesirable undulations in the vehicle speed.

[0108] As in the first and second embodiments, as soon as a movement of the clutch pedal 27 towards the disengaged position has been detected, the control system moves the connecting clutch 6 towards its fully disengaged position until a slipping position, in which said connecting clutch 6 transmits a drag torque between the crankshaft of the internal combustion engine 3 and the intermediate shaft 7.

[0109] Subsequently, the control system detects a movement of the control element 32 of the gearbox 10 (third curve 52) representative of a gear change, during phase III. If the new gear engaged is a higher gear than the previous one, as illustrated in [Fig. 8], the control system controls the internal combustion engine 3 so that its speed (ninth curve 58) is controlled by Vengin = V0 + Cl; with: - V0: the speed of the input shaft 9 of the gearbox 10 (tenth curve 59); and - Cl: a constant, for example between 1 and 50 revolutions per minute.

[0110] Conversely, if the new gear engaged is a lower speed ratio than the previous one, as illustrated in [Fig. 9], the control system controls the internal combustion engine 3 so that its speed (tenth curve 59) is controlled by Vengine = V0 - C2; with: - V0: the speed of the input shaft 9 of the gearbox 10 (tenth curve 59); and - C2: a constant, for example between 1 and 50 revolutions per minute.

[0111] With the connecting clutch 6 in a slipping position, it also ensures the increase or decrease of the speed of the intermediate shaft 7.

[0112] During phase IV, the control system compares the rotational speed of the input shaft 9 of the gearbox 10 (tenth curve 59) to that of the intermediate shaft 7 (eleventh curve 60). As soon as the crankshaft of the internal combustion engine 3 and the input shaft 9 of the gearbox 10 are synchronized, the connecting clutch 6 is driven so as to synchronize the crankshaft of the internal combustion engine 3 (ninth curve 58) with the intermediate shaft 7 (eleventh curve 60) and then moved up to its maximum transmissible torque capacity (seventh curve 56).

[0113] Figure 11 illustrates the implementation of a control method according to a fourth embodiment during a speed change to a gear ratio of higher speed.

[0114] In this fourth embodiment, the control method is simplified in that it only acts on the connecting clutch 6 and the electric machine 5 to limit undesirable undulations in the vehicle speed.

[0115] The method implemented differs from that described above in relation to figures 4 and 5 only in that, during phase IV, the torque of the heat engine 3 (fourth curve 53) is not controlled according to a setpoint for the difference in speed between the speed of the heat engine 3 (ninth curve 58) and the speed of the intermediate shaft 7 (eleventh curve 60).

[0116] Although the invention has been described in connection with several particular embodiments, it is clearly evident that it is by no means limited to them and that it includes all technical equivalents of the means described as well as their combinations if these fall within the scope of the invention, as defined by the claims.

[0117] The use of the verb "comprise", "comprendre" or "include" and its conjugated forms does not exclude the presence of other elements or steps than those stated in a claim.

[0118] In the claims, any reference sign in parentheses shall not be interpreted as a limitation of the claim.

Claims

Demands

1. Method of controlling a propulsion system, said propulsion system comprising: - a heat engine (3); - an intermediate shaft (7) coupled to an electrical machine (5); - a movable connecting clutch (6) between an engaged position in which said connecting clutch (6) couples the internal combustion engine (3) to the intermediate shaft (7) and a disengaged position in which the internal combustion engine (3) and the intermediate shaft (7) are disengaged from each other; - a gearbox (10) which includes an input shaft (9) and which is controlled by a control element (32); - a main clutch (11) which is movable between an engaged position in which said main clutch (11) couples the intermediate shaft (7) to the input shaft (9) and a disengaged position in which the intermediate shaft (7) and the input shaft (9) are disengaged; said main clutch (11) being controlled by a clutch pedal (27) movable between a released position in which the main clutch (11) is in the engaged position and a depressed position in which the main clutch (11) is in the disengaged position; the control process comprising the following successive steps: - detecting a movement of the control element (32) towards a neutral position; - move the connecting clutch (6) into a slipping position in which said connecting clutch (6) ensures relative rotation between the internal combustion engine (3) and the intermediate shaft (7) in response to the detection of the movement of the control member (32) towards the neutral position; - detect an event representative of a synchronization of the intermediate tree (7) and the input tree (9); and - move the connecting clutch (6) from said slipping position towards the engaged position in response to the detection of said event representative of a synchronization of the intermediate shaft (7) and the input shaft (9).

2. A control method according to claim 1, comprising prior to the detection of the displacement of the control member (32) towards the neutral position, the following steps: - detect an event representative of a movement of the main clutch (11) from the engaged position towards the disengaged position; and - move the connecting clutch (6) from the engaged position towards the disengaged position to a setpoint position in which the connecting clutch (6) does not slip, in response to the detection of the event representative of a movement of the main clutch (11) from the engaged position towards the disengaged position.

3. A control method according to claim 1 or 2, wherein, in response to the detection of the movement of the control member (32) towards the neutral position, the internal combustion engine (3) and / or the connecting clutch (6) are controlled so as to control a speed difference between an internal combustion engine speed (3) and an intermediate shaft speed (7) to a setpoint value.

4. A control method according to any one of claims 1 to 3, wherein an event representative of a displacement of the main clutch (11) from the engaged position towards the disengaged position beyond a threshold is detected and the electric machine (5) is controlled as a function of a speed of the input shaft (9) until the event representative of a synchronization of the intermediate shaft (7) and the input shaft (9) is detected.

5. A control method according to claim 4, wherein in response to the detection of the event representing a synchronization of the intermediate shaft (7) and the input shaft (9), the electric machine (5) is controlled in torque according to a decreasing torque setpoint and the internal combustion engine (3) is controlled according to said decreasing torque setpoint of the electric machine in order to compensate for the decrease in the torque of the electric machine and a signal representing a position of an accelerator pedal (17).

6. A control method according to any one of claims 1 to 3, wherein an event representative of a displacement of the main clutch (11) from the engaged position towards the disengaged position beyond a threshold is detected, and the internal combustion engine (3) is controlled as a function of a variable representative of the speed of the input shaft (9) so as to maintain a rotation of said internal combustion engine (3) until an event representative of a synchronization of the intermediate tree (7) and the input tree (9).

7. Control system of a propulsion system, said propulsion system comprising: - a heat engine (3); - an intermediate shaft (7) coupled to an electrical machine (5); - a movable connecting clutch (6) between an engaged position in which said connecting clutch (6) couples the internal combustion engine (3) to the intermediate shaft (7) and a disengaged position in which the internal combustion engine (3) and the intermediate shaft (7) are disengaged from each other; - a gearbox (10) which includes an input shaft (9) and which is controlled by a control element (32); - a main clutch (11) which is movable between an engaged position in which said main clutch (11) couples the intermediate shaft (7) to the input shaft (9) and a disengaged position in which the intermediate shaft (7) and the input shaft (9) are disengaged; said main clutch (11) being controlled by a clutch pedal (27) movable between a released position in which the main clutch (11) is in the engaged position and a depressed position in which the main clutch (11) is in the disengaged position; said control system being configured to: - detect a movement of the control member (32) towards a neutral position; - move the connecting clutch (6) into a slipping position in which said connecting clutch (6) ensures relative rotation between the internal combustion engine (3) and the intermediate shaft (7) in response to the detection of the movement of the control member (32) towards the neutral position; - detect an event representative of a synchronization of the intermediate tree (7) and the input tree (9); and - move the connecting clutch (6) from said slipping position towards the engaged position in response to the detection of said event representative of a synchronization of the intermediate shaft (7) and the input shaft (9).

8. Control system according to claim 7, configured for - detect an event representative of a movement of the main clutch (11) from the engaged position towards the disengaged position; and - move the connecting clutch (6) from the engaged position towards the disengaged position to a setpoint position in which the connecting clutch (6) does not slip, in response to the detection of the event representative of a movement of the main clutch (11) from the engaged position towards the disengaged position.

9. Control system according to claim 7 or 8, configured to control the internal combustion engine (3) and / or the connecting clutch (6) so as to control a speed difference between an internal combustion engine speed (3) and an intermediate shaft speed (7) to a setpoint value in response to the detection of the movement of the control member (32) towards the neutral position.

10. Control system according to any one of claims 7 to 9, configured to: - detect an event representative of a movement of the main clutch (11) from the engaged position towards the disengaged position beyond a threshold; and - control the electric machine (5) as a function of a variable representative of a speed of the input shaft (9) until the event representative of a synchronization of the intermediate shaft (7) and the input shaft (9) is detected.

11. Control system according to claim 10, configured to: - control the electric machine (5) in torque according to a decreasing torque setpoint in response to the detection of the event representative of a synchronization of the intermediate shaft (7) and the input shaft (9), and - control the internal combustion engine (3) according to said decreasing torque setpoint of the electric machine in order to compensate for the decrease in the torque of the electric machine and a signal representative of a position of an accelerator pedal (17).

12. A control system according to any one of claims 7 to 9, configured to: - detect an event representing a movement of the main clutch (11) from the engaged position towards the disengaged position beyond a threshold; and - control the internal combustion engine (3) as a function of a variable representing a speed of the input shaft (9) until the event representing an intermediate shaft synchronization (7) and the input tree (9) is detected.

13. Motor vehicle comprising: - a heat engine (3); - an intermediate shaft (7) coupled to an electrical machine (5); - a movable connecting clutch (6) between an engaged position in which said connecting clutch (6) couples the internal combustion engine (3) to the intermediate shaft (7) and a disengaged position in which the internal combustion engine (3) and the intermediate shaft (7) are disengaged from each other; - a gearbox (10) which includes an input shaft (9) and which is controlled by a control element (32); - a main clutch (11) which is movable between an engaged position in which said main clutch (11) couples the intermediate shaft (7) to the input shaft (9) and a disengaged position in which the intermediate shaft (7) and the input shaft (9) are disengaged; said main clutch (11) being controlled by a clutch pedal (27) movable between a released position in which the main clutch (11) is engaged and a depressed position in which the main clutch (11) is disengaged; and - a control system according to any one of claims 7 to 12.

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